The present invention is directed to an earth drilling device for taking earth samples having a rotatable drilling tube which supports a drill bit which in turn is provided with recessed depressions which accept an exchangeable plastic sleeve which serves as a sample container.
A device for taking earth samples is known from CH-Pat. No. 543.781. A sample container disclosed therein is a cylindrical sleeve made of a plastic material having a securely attached floor which is situated above during the drilling process. To allow trapped air to escape the sleeve as the drill core penetrates the sleeve the floor is perforated. These smooth walled sleeves, closed on one side of the floor, must be sufficiently rigid to be stored and transported and thus must have relatively thick walls. They also take up a considerable amount of space. Cylindrical, slip-on caps are provided to close off the earth sample lying in the sleeve. These caps, too, require a relatively large amount of space in storage and transportation.
The present invention provides a simple means which avoids these disadvantages. To this end the apparatus according to the present invention is characterized by the utilization of a sleeve which is open at both ends and comprises a thin plastic film which can be temporarily compressed flat for storage and transporting purposes and then expanded to a round cross-section when inserted into the drill tube. Two identical caps provided with conical slip-on collars are utilized for sealing both ends of the sleeve. A particularly advantageous sleeve form is characterized by the fact that the sleeve exhibits a polygonal cross-section. However, due to a large number of axis-parallel bends uniformly distributed around its circumference, it fits in conformity with the inner surface of the drill tube.
These sleeves are simple to produce, e.g., by longitudinally folding a flat cut-out, rolling it up and gluing or welding it along an overlapping seam. Such a sleeve could be easily folded more or less flat along to diametrically opposing folds for transportation or storage and opened into a round shape again for use within the drilling tube. The slight deformation or increased bending along two sleeve lines resulting from light flattening or bending can be smoothed out sufficiently by hand again that the sleeve assumes the desired round shape by itself when it is pushed into the drill tube.
The numerous folds in the longitudinal direction of the sleeve cause a certain stiffening of the sleeve so that it can be easily produced from a somewhat thinner film than is customary when using smooth-walled sleeves. The two associated caps provided for the polygon sleeve are not placed on the ends of the sleeve until the sleeve containing the drill sample is removed from the drill tube. The caps are purposely, slightly conical, thereby assuring not only that they seat securely on the sleeve but also that they can be stacked to save space by inserting one cap into an identical cap below it for storage and transportation purposes.
It has proven to be particularly advantageous to work with several telescoping drill tubes, whereby sleeves with correspondingly smaller diameter are associated with each inner, deeper-penetrating drill tube. Thus, for example, earth samples up to several meters in depth are possible with sleeve segment lengths of 25 cm. Since a large number of sleeves is necessary in such cases, the mentioned, space saving transportable and storable polygon sleeves and their associated caps afford particular advantages.
It has been shown that earth samples taken at depths down to several meters are possible with a drilling device of the present type. It has been shown to be particularly advantageous to construct the drill tube as a multi-part telescopic tube in which the inner or innermost, deepest extending tube section is inserted into the next outer tube. This, of course, requires that the drill core sections, packed by means of the outer drill tube section in corresponding number of sleeve sheaths, be removed first. Then this outer, empty drill tube section is lowered again and now serves as a guide for the inner drill tube section with which the deeper earth samples in correspondingly smaller sample containers can be removed. It has been shown that this method can lead to problem-free samples only when the individual samples can be removed with the drill tube remaining in the earth. This is not possible with the conventional arrangement of the sample container directly on an inner shoulder in the drill tube formed by an offset in the latter. However, this problem is solved according to the present invention wherein an insert cylinder in the drill tube is adapted to accept the sample container by means of a rod extending from above. A device of this type for deep drilling is not only relatively heavy, but also requires a relatively strong, and therefore, heavy drive motor. With the conventional arrangement of the motor coaxially above the drill tube, the heavy motor must be removed when each sample is removed. This problem too is solved, according to the present invention, by the fact that the drill tube and its associated drive mechanism are supported by a waist plate. The drive motor is situated to the side of a coupling head disposed coaxial to the drill tube and is connected thereto. Thus, the sample container can be removed from the drill tube without separating the coupling head from the drill tube. This cuts down consideraly on the time needed to remove samples from greater depths of several meters or more.